1. Field of the Invention
A double path microdrop optical biometric system is provided for bio-chemical tests. It has the advantages and functions including the required volume of the specimen (or called sample) is small and the precision will be doubled by the double path design. The entire optic-electronic system is simple and at low cost. By using the LEDs (light emitting diodes), it can avoid the use of filter and the over-heating problem. Moreover, the system can execute various bio-chemical tests.
2. Description of the Prior Art
The conventional bio-chemical detecting methods include two methods. One method is to use a detector to measure the change of voltage that is converted from the bio-chemical energy. The other method is to use the testing agent applied on the specimen. For example, a chemical testing agent or testing paper can be used to measure the density of a target object in the specimen. After which, a quantitative analysis can be done by using some optical techniques.
The first method is easy, compact, fast, and no pollution generated by the testing agent or paper. However, its disadvantages include low precision and not suitable for repeated testing.
The second method is good in the quantitative analysis and suitable for mass detection. It is widely used in different automatic detecting equipments in the bio-chemical industry. Also, it is the major method used in current medical and bio-chemical related fields. But, its disadvantages include the testing device is complex, it is not suitable for dynamic testing, it will cause certain pollution from the testing agent, and its operation is complicated. The basic principle of the optical technique is to measure the absorption as a scale to determine the density of a specific colored object in the specimen. Furthermore, it can be classified into the following methods, such as colorimetric analysis method, spectral analysis method, fluorescent analysis method, turbidity analysis method, etc. The devices about all these methods are quite similar to the conventional spectrometer.
The current commercial spectrometer for bio-chemical testing has many kinds. The large spectrometer is expensive and occupies a huge space. However, the micro spectrometer is light-weighted, small, fast, easy to operate, suitable for mass detection and non-expensive. But, its precision and sensitivity is not good due to the technical limitation of its micro detector. So, it is still not suitable for most bio-chemical testing.
Referring to FIG. 1, it illustrates the structure of a conventional micro spectrometer. It contains two parts, namely the optical system and the electrical system (not shown). The optical system includes a traditional light source having the tungsten filament 91, an condenser 92, a slit 93, an self-focusing blazed reflection grating 94, a detector 95. The traditional light source 91 provides an enough light (or beam) for the micro spectrometer and will cover the wavelength range of the detector 95. The condenser 92 can collected the incoming light into the micro spectrometer. Also, the numerical aperture (N.A.) value should match with the one of the used fiber optics. The function of the corner cube array 94 is to separate the light with different wavelength ranges and to converge the reflected lights to the detector 95. The detector 95 can detect the light intensity and distribution and then converted into electrical signals for further analog output processing.
No matter the conventional spectrometer is the large one or the micro one, the container must be the standard rectangular quartz made container (the bottom is one centimeter square and the depth is one centimeter, so the volume is 1 cc). Therefore, the require volume is relative large.
Assume that the user is located in an area or country where it is under the danger of Severe Acute Respiratory Syndrome (briefly called SARS hereafter) virus. If the user (of a medical organization) needs to collect the sputum of a patient, the user has to collect at least 1 cc to conduct a bio-chemical testing. In case the user only collects 0.5 cc of the patient's sputum, the test cannot be done by the conventional spectrometer because the volume is fewer than the require minimum 1 cc. Hence, the user will miss the best time for determine whether this patient is a SARS patient or not. It not only is disadvantageous for the patient, but also increases the uncertainty and panic for the society.
However, if the user simply reduces the required volume down to 0.5 cc, it will cause another problem that the sensitivity of the entire system becomes one half of the original one. Therefore, the testing becomes unreliable.
Besides, because different coloring agents have different light absorption characteristics, an additional filter has to be added on the conventional light source so that a particular wavelength range can be selected. However, after using the filter for a long period, it will cause the over-heating problem.
Thus, the disadvantages of the conventional spectrometer can be summarized as follows:                [1] the required volume of the specimen is relative large;        [2] the entire optical system is complex and expensive;        [3] the sensitivity of one-path penetration through the specimen is low; and        [4] the conventional tungsten-typed light source needs another filter that causing the over-heating problem.        